Calculate expected value for coin flips
Last updated: May 14, 2026
Quick Overview
Given the following scenario about revenue per session, calculate the the sample size needed.
SentinelOne
May 14, 202650
9
119 solved
Given the following scenario about revenue per session, calculate the the sample size needed.
This statistics question from SentinelOne's Take-home Project tests your ability to apply mathematical reasoning to practical problems. The interviewer expects precise definitions, correct methodology, and awareness of assumptions and limitations.
What the Interviewer Expects
- Derive results from first principles when needed
- Handle complex scenarios with multiple interacting variables
- Design experiments that account for real-world complications
- Discuss advanced topics: Bayesian methods, causal inference, resampling
- Connect statistical concepts to business decision-making
- Identify subtle errors in reasoning (Simpson's paradox, survivorship bias)
Key Topics to Cover
How to Approach This
- Define your hypotheses (H0 and H1) clearly before performing any test.
- Calculate required sample size BEFORE running an experiment, using power analysis.
- Remember the Central Limit Theorem: sample means become approximately normal with large n.
- Watch for Simpson's paradox. Always segment data by key dimensions.
- Distinguish between statistical significance and practical significance.
Possible Follow-up Questions
- How would you explain this result to a non-technical audience?
- What if the sample size is very small?
- How would you design a follow-up experiment based on these results?
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Problem Formulation
To determine the expected revenue per session from a series of coin flips, we need to define the parameters of the problem. Let's assume:
- Each coin flip results in either a Heads (H) or Tails (T). -...
Solution Approach
To calculate the required sample size (n) for estimating the expected revenue E[R] within a specified margin of error (E) at a confidence level defined by Z-score (Z), we can employ the formula for th...
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